Design and analysis of optical coupler with a stable splitting ratio based on cascaded multistage directional couplers

Abstract

An optical 3 dB coupler based on cascaded three-stage directional couplers is proposed. The optical coupler with a finite impulse response on optical power is able to provide a stable 50% splitting ratio. The influence of the waveguide gap, width of each waveguide, and coupling length on the performance of the proposed coupler is illustrated. The numerical analysis and results show the reported coupler with less sensitivity to such fabrication variations. The proposed optical coupler could also be designed with any stable splitting ratio for optical communication applications.